The correct answer is option B, hydrogen.
The majority of the atmospheric gases are found in the sea water solution. In supplementation to oxygen and nitrogen, the most profusely found gas in the atmosphere, that is, carbon dioxide is found in the ample concentrations in the ocean waters.
However, hydrogen is not present, and if found it is found in minute concentration. Of the gases, nitrogen is the most abundant gas found in seawater, while oxygen is the second most abundant, and carbon dioxide is the most soluble gas, and one of the various constituents, which influences the pH balance of the ocean.
Planarian<span>, </span><span>any of a group of widely distributed, mostly free-living flatworms of the class Turbellaria
These are elongated and ciliated
Mouth is middle of the body
hope it helps</span>
